Neurodevelopmental disabilities and mental health disorders are prevalent and have been steadily increasing in US children over the last 2 decades. Worldwide pesticide use is at an all-time high as agricultural mass production continues to expand. People are exposed to pesticides through fumigated food, pest control in their homes and communities, and during certain approved treatments for lice and scabies. The most commonly used classes of insecticides worldwide are neonicotinoids and cholinesterase inhibitors, including organophosphate and carbamates. Older pesticides, such as organochlorines, are of present concern because they are persistent and are still detected in the environment and people, even though many were banned 40 years ago. Organophosphates, and to a lesser extent organochlorines, have been associated with neurobehavioral delays in children and there is growing evidence that boys are more sensitive to exposures than girls. Neonicotinoids have not been studied in this context among children. In 2008, we examined 313 children (ages 4-9 y) living in floricultural communities in Ecuador in the Secondary Pesticide Exposure on Children and Adolescents (ESPINA) study. The objective of the proposed study is to conduct a follow-up of ESPINA participants in 2016 and supplement the sample with new volunteers for a total of 410 participants (ages 12-17 y). We will assess, longitudinally, the associations of pesticide exposures with neurobehavior and symptoms of anxiety and depression. We propose 2 exams: an Abbreviated exam during the peak of Mother's Day flower production (Apr 2016) and a Full exam soon after the harvest (Jul/Aug 2016). We will investigate the following associations (hypotheses): 1) Pesticide exposures (cholinesterase inhibitors, neonicotinoids and OCPs) are associated with long-term neurobehavioral alterations, and will assess whether boys are more susceptible than girls. 2) Pesticide exposures are associated with anxiety and depression symptoms. 3) Pesticide exposures are associated with transient neurobehavioral alterations. We will assess change of AChE activity and scores of attention and inhibition between the Abbreviated and Full exams. We will also test whether time since the flower harvest is positively associated with neurobehavioral performance in the full battery of assessments. As a secondary aim, we will assess whether adrenal and sex hormones modify the associations of pesticide exposures with mental health outcomes. Impact: Few epidemiologic studies have assessed pesticide exposures in relation to mental health for extended periods of time, and we know of no published studies on adolescents. ESPINA 2016 will address how pesticide exposure relates to mental health symptoms longitudinally, and will provide, for the first time, repeated assessments of short-term neurobehavioral changes associated with pesticide exposures in children.